The present invention relates to a method and apparatus for delivering laser energy to an object. The invention is particularly useful, and is therefore described below, with respect to applications for recording or/and ablating information, etc., or for producing two or more separated laser beams from diode lasers, e.g., to be used for simultaneous recording.
Diode lasers constitute a preferred laser beam source for many diverse applications, including recording, cutting, ablating, etc., since they have the advantages of compact size, high efficiency, high reliability, and/or manufacturability, as compared to other solid-state and gas laser devices. Laser recording devices employing diode lasers are known in the art. For example, U.S. Pat. No. 5,309,178 discloses a laser recording apparatus including a diode laser, beam compression means, a multichannel acousto-optic modulator, and imaging means for directing the laser energy from the modulator to a laser recording image plane.
Diode lasers, however, have a power density limitation dictated largely by heat removal considerations. These limitations restrict the optical power per unit area that can be generated by the laser. In addition, the divergence of the source is large for a broad area. The limitations of power density and angular divergence substantially limit the source brightness capability of such diode lasers.
As known, a diode laser array with typical dimensions of one micron, by several hundreds or more microns, emits at higher power than corresponding diffraction limited source. However, the length of a single p-n junction is limited by certain thermal conditions, and therefore practical high power diode lasers are often constructed of a plurality of separated active segments aligned in a line.